[RFC PATCH V2 03/13] block: add helper of blk_create_io_context

[Ming Lei <ming.lei@redhat.com>]

Add one helper for creating io context and prepare for supporting
efficient bio based io poll.

Meantime move the code of creating io_context before checking bio's
REQ_HIPRI flag because the following patch may change to clear REQ_HIPRI
if io_context can't be created.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 block/blk-core.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index a31371d55b9d..d58f8a0c80de 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -792,6 +792,18 @@ static inline blk_status_t blk_check_zone_append(struct request_queue *q,
 	return BLK_STS_OK;
 }
 
+static inline void blk_create_io_context(struct request_queue *q)
+{
+	/*
+	 * Various block parts want %current->io_context, so allocate it up
+	 * front rather than dealing with lots of pain to allocate it only
+	 * where needed. This may fail and the block layer knows how to live
+	 * with it.
+	 */
+	if (unlikely(!current->io_context))
+		create_task_io_context(current, GFP_ATOMIC, q->node);
+}
+
 static noinline_for_stack bool submit_bio_checks(struct bio *bio)
 {
 	struct block_device *bdev = bio->bi_bdev;
@@ -836,6 +848,8 @@ static noinline_for_stack bool submit_bio_checks(struct bio *bio)
 		}
 	}
 
+	blk_create_io_context(q);
+
 	if (!blk_queue_poll(q))
 		bio->bi_opf &= ~REQ_HIPRI;
 
@@ -876,15 +890,6 @@ static noinline_for_stack bool submit_bio_checks(struct bio *bio)
 		break;
 	}
 
-	/*
-	 * Various block parts want %current->io_context, so allocate it up
-	 * front rather than dealing with lots of pain to allocate it only
-	 * where needed. This may fail and the block layer knows how to live
-	 * with it.
-	 */
-	if (unlikely(!current->io_context))
-		create_task_io_context(current, GFP_ATOMIC, q->node);
-
 	if (blk_throtl_bio(bio)) {
 		blkcg_bio_issue_init(bio);
 		return false;
-- 
2.29.2